Вставьте необходимый глагол: didn't have to, was to, cannot, must, couldn't, be able to, need to, were allowed, needn't,

1. The children cannot carry this box: it is too heavy. 2. You must work hard at your English. 3. It was Sunday yesterday and we didn\'t have to go to work. 4. I need to wait for her at the station. 5. She was to send a telegram because it was too late to send a letter. 6. I couldn\'t understand what he said. 7. When her arm is better she will be able to play the piano again. 8. The children were allowed to watch TV last night. 9. Nick needn\'t write to hers for she will be here tomorrow. 10. May I see your garden, please?